Wireless communication method and apparatus for processing enhanced uplink scheduling grants

ABSTRACT

A method and apparatus for processing enhanced uplink scheduling grants are disclosed. A wireless transmit/receive unit (WTRU) detects an absolute grant (AG) and a relative grant (RG). Once the WTRU detects an AG or a RG, a new serving grant (SG) is generated and a hybrid automatic repeat request process may be activated or deactivated depending on whether the received AG is a primary AG or a secondary AG, whether a scheduling mode is a primary AG mode or a secondary AG mode, whether an AG value is set to “INACTIVE” and whether a transmission time interval is 2 ms or 10 ms. A Node-B may send a secondary AG to the WTRU before switching from a primary AG mode to a secondary AG mode and may send the secondary AG only if there is no out-of-date secondary AG exists, which may be detected by implementing a time threshold.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.60/712,307 filed Aug. 30, 2005, which is incorporated by reference as iffully set forth.

FIELD OF INVENTION

The present invention is related to a wireless communication system.More particularly, the present invention is related to a method andapparatus for processing enhanced uplink (EU) scheduling grants.

BACKGROUND

EU is one of the major features in the third generation partnershipproject (3GPP) system. EU offers a peak data rate of 5.76 Mbps. In orderto support EU operation, several downlink physical channels, such as anenhanced dedicated channel e(E-DCH) absolute grant channel (E-AGCH) andan E-DCH relative grant channel (E-RGCH), are provided to transmitcontrol information.

FIG. 1 is a block diagram of a conventional wireless communicationsystem 100 which supports EU. The system 100 comprises a wirelesstransmit/receive unit (WTRU) 102, a Node-B 104 and an RNC 106. The RNC106 controls overall E-DCH operation by configuring E-DCH parameters forthe Node-B 104 and the WTRU 102, such as initial transmit power level,maximum allowed transmit power or power ratio, or available channelresources per Node-B. Between the WTRU 102 and the Node-B 104, an E-DCH108, an E-DCH dedicated physical control channel (E-DPCCH), an E-AGCH112, an E-RGCH 114 and an E-DCH hybrid automatic repeat request (H-ARQ)indicator channel (E-HICH) 116 are established for supporting E-DCHoperations.

For E-DCH transmissions, the WTRU 102 sends scheduling requests, (alsoknown as rate requests), for the logical channels which a radio resourcecontrol (RRC) determines that reporting is needed to be made to theNode-B 104 via the E-DCH 108. The scheduling requests are transmitted inthe form of scheduling information and a happy bit. The happy bit istransmitted via the E-DPCCH 110 whenever the E-DPCCH 110 is transmitted.The Node-B 104 sends a scheduling grant, (i.e., an absolute grant (AG)or a relative grant (RG)), to the WTRU 102 via the E-AGCH 112 or theE-RGCH 114. The AG is sent by an E-DCH serving cell, and the RG is sentby either an E-DCH serving radio link set (RLS) or an E-DCH non-servingradio link (RL). The E-DCH serving cell is a cell from which the WTRUreceives AGs from a Node-B scheduler. A WTRU has one E-DCH serving cell.The E-DCH serving RLS is a set of cells which contains at least theE-DCH serving cell and from which the WTRU shall receive an AG. The WTRUhas only one serving RLS. The non-serving RL is a cell which belongs tothe E-DCH active set but does not belong to the serving RLS and fromwhich the WTRU may receive an RG. The WTRU may have zero, one or severalnon-serving RL(s).

After E-DCH radio resources are allocated for the WTRU 102, the WTRU 102transmits uplink data via the E-DCH 108. In response to E-DCH or E-DPCCHtransmissions, the Node-B 104 sends an acknowledgement (ACK) or anon-acknowledgement (NACK) message for H-ARQ operation via the E-HICH116.

The E-AGCH 112 carries an AG which includes an AG value and anactivation flag. The AG value is provided in the form of a maximum powerratio for the WTRU. The maximum power ratio is given by the ratio ofE-DCH dedicated physical data channel (E-DPDCH) over dedicated physicalcontrol channel (DPCCH) power. The activation flag is used to activateor deactivate the H-ARQ processes. The activation flag may be set toeither “SINGLE” or “ALL.” If the activation flag is set to “SINGLE”, asingle H-ARQ process is activated or deactivated. If the activation flagis set to “ALL”, all H-ARQ processes are activated or deactivated.

The E-RGCH 114 carries an RG. The RG indicates power (or power ratio) upor down commands to adjust the absolute grant. The serving RLS may sendUP, DOWN or HOLD commands and the non-serving RL may send DOWN or HOLDcommands. The UP, DOWN or HOLD commands indicate an increase, decreaseor no change of the maximum allowed power ratio of the WTRU for thescheduled transmission of data, respectively. The commands fromdifferent non-serving RLs are independent and may be different from oneanother. The E-DCH non-serving RLs send the RG to prevent systemoverloading in data traffic and maintain the intra-cell and inter-cellinterference at the required level.

A network may control single WTRU or a group of WTRUs via the E-AGCH,the E-RGCH, or both. When in a primary AG mode, the Node-B controls theresource scheduling for only a particular WTRU via the E-AGCH. When in asecondary AG mode, the Node-B controls the resource scheduling for agroup of WTRUs via the E-AGCH. The E-AGCH is transmitted with an E-DCHradio network temporary identifier (E-RNTI). Two E-RNTIs may beconfigured for the WTRU at a time. One is a primary E-RNTI and the otheris a secondary E-RNTI. Only one E-RNTI may be transmitted in the air ata time. The WTRU should monitor both E-RNTIs if the WTRU is configuredwith both E-RNTIs.

The WTRU calculates and sets a serving grant (SG) based on the receivedAG and RG. A successful detection and decoding of the E-AGCH 112 and theE-RGCH 114 and proper setting of the SG are important for theperformance of systems and the performance of EU. Therefore, it isdesirable to have a method and apparatus for efficiently detecting anddecoding the AG and RGs and processing the SG.

SUMMARY

The present invention is related to a method and apparatus forprocessing EU scheduling grants. A WTRU detects a scheduling grantincluding at least one of an AG or an RG. Once the WTRU detects an AG oran RG, a new SG is generated and an H-ARQ process may be activated ordeactivated depending on whether the received AG is a primary AG or asecondary AG, whether a scheduling mode is a primary AG mode or asecondary AG mode, whether an AG value is set to “INACTIVE” and whethera transmission time interval (TTI) is 2 ms or 10 ms. A Node-B may sendeither a primary AG or a secondary AG to a WTRU.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding of the invention may be had from thefollowing description, given by way of example and to be understood inconjunction with the accompanying drawings wherein:

FIG. 1 is a block diagram of a conventional wireless communicationsystem;

FIG. 2 is an exemplary block diagram of a WTRU configured in accordancewith the present invention;

FIG. 3 is a flow diagram of a process of processing SGs in accordancewith the present invention;

FIGS. 4A and 4B, taken together, are a flow diagram of a process ofgenerating SGs based on scheduling grant from the serving RLS inaccordance with one embodiment of the present invention;

FIGS. 5A-5C illustrates transmission and reception for AGs andprocessing SGs in accordance with the present invention;

FIG. 6 is a block diagram of a Node-B configured in accordance with thepresent invention; and

FIGS. 7A and 7B, taken together, are a flow diagram of a process ofgenerating SGs based on scheduling grant from the serving RLS inaccordance with another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

When referred to hereafter, the terminology “WTRU” includes but is notlimited to a user equipment (UE), a mobile station, a fixed or mobilesubscriber unit, a pager, or any other type of device capable ofoperating in a wireless environment. When referred to hereafter, theterminology “Node-B” includes but is not limited to a base station, asite controller, an access point (AP) or any other type of interfacingdevice in a wireless environment.

The features of the present invention may be incorporated into anintegrated circuit (IC) or be configured in a circuit comprising amultitude of interconnecting components.

FIG. 2 is an exemplary block diagram of a WTRU 200 configured inaccordance with the present invention. The WTRU 200 includes an E-AGCHdecoder 202, an E-RGCH decoder 204 and an SG processor 206. The E-AGCHdecoder 202 receives, and decodes, E-AGCH signals 201 a received fromthe serving RLS to detect an AG 205 a. The detected AG 205 a is sent tothe SG processor 206. The E-RGCH decoder 204 receives, and decodes,E-RGCH signals 201 b from the serving RLS and E-RGCH signals 201 c fromthe non-serving RL(s) to detect an RG 205 b from the serving RLS and anRG 205 c from the non-serving RL(s), respectively. The detected RGs 205b, 205 c are sent to the SG processor 206. The E-AGCH decoder 202indicates to the SG processor 206 whether the AG 205 a was received witha primary E-RNTI or a secondary E-RNTI. The E-AGCH 202 and the E-RGCH204 also indicate which sub-frame the scheduling grant, (i.e., AG 205 aor RG 205 b, 205 c), was received in.

The SG processor 206 generates a current SG based on the AG and/or theRG. The SG processor 206 includes a first SG calculator 208, a second SGcalculator 210 and a controller 212. The first SG calculator 208receives an AG 205 a and an RG 205 b from the serving RLS and calculatesa first SG candidate 209 a. The second SG calculator 210 receives atleast one RG 205 c from the non-serving RL(s) and calculates a second SGcandidate 209 b. The controller 212 outputs a new SG 213 based on thefirst SG candidate 209 a and/or the second SG candidate 209 b.

When the WTRU 200 is in an idle state, the SG processor 206 may betemporarily turned off for power saving. The latest received secondaryAG and the primary AG are saved in a memory (not shown in FIG. 2) andthe SG processing resumes when the WTRU 200 is activated and has datafor transmission. After resuming the SG processing, the saved latestreceived secondary AG and the primary AG are processed by the SGprocessor 206 and a new SG 213 is generated.

The scheduling grant processor 206 provides the amount of power that canbe used by a transport format combination (TFC) selection andmultiplexing unit (not shown) for scheduled data dedicated channelmedium access control (MAC-d) flows. This may be identified as the ratioto the DPCCH power. Alternatively, this may be identified by the maximumtransmit power that can be used for scheduled data to avoid the TFCselection and multiplexing unit to be aware of the DPCCH powermeasurements. The latter method is preferable since other schedulingrelated entities do not have to know the current DPCCH power.

FIG. 3 is a flow diagram of a process 300 of processing SGs inaccordance with the present invention. A WTRU monitors schedulinggrants, (i.e., an AG and an RG), from a serving RLS and at least onenon-serving RL (step 302). It is then determined whether there is an AGor an RG received from the serving RLS (step 304). If there is an AG oran RG received from the serving RLS, a first SG candidate is calculatedbased on the AG and/or the RG that come from serving RLS (step 306). Itis then determined whether there is a DOWN command received from thenon-serving RL(s) (step 308). If no DOWN commands are received from thenon-serving RL(s), a new SG is set to the first SG candidate (step 310)and the process 300 waits for the next transmission time interval (TTI)at step 322 before proceeding to step 304. If there is a DOWN commandreceived from the non-serving RL(s), a second SG candidate is calculatedbased on the received DOWN command and a previous SG (step 312). A newSG is then set to a minimum one of the first SG candidate and the secondSG candidate (step 314) and the process 300 waits for the next TTI atstep 322 before proceeding to step 304. The new SG may be set to theminimum of the first SG candidate and the second SG candidate becausethe serving cell may reduce the scheduling grant by more than the RGdown step size.

If, in step 304, it is determined that there is no AG or RG receivedfrom the serving RLS, it is further determined whether there is a DOWNcommand received from the non-serving RL(s) (step 316). If there is noDOWN command received from the non-serving RL, the process 300 returnsto step 302 to monitor the scheduling grants. If there is a DOWN commandreceived from the non-serving RL, a second SG candidate is calculatedbased on the DOWN command and a previous SG (step 318). A new SG is thenset to the second SG candidate (step 320) and the process 300 waits forthe next TTI at step 322 before proceeding to step 304.

FIGS. 4A and 4B, taken together, are a flow diagram of a process 400 ofgenerating SGs based on a scheduling grant from the serving RLS inaccordance with one embodiment of the present invention. A schedulinggrant from a serving RLS is detected (step 402). It is determinedwhether an AG is detected (step 404). If it is determined that an AG isdetected, a new SG may be generated and/or an H-ARQ process may becomeactive or inactive depending on whether the received AG is a primary AGor a secondary AG, whether a scheduling mode is a primary AG mode or asecondary AG mode, whether an AG value is set to “INACTIVE” and whetherthe TTI is 2 ms or 10 ms.

An AG may be either a primary AG or a secondary AG. The primary AG is anAG received with a primary E-RNTI and the secondary AG is an AG receivedwith a secondary E-RNTI. The primary AG always resets the current SG.The secondary AG resets the current SG only if the WTRU is in asecondary AG mode. The WTRU is switched to a secondary AG mode if 1) for10 ms TTI the AG value of the last primary AG was set to “INACTIVE”, and2) for 2 ms TTI the AG value of the last primary AG was set to“INACTIVE” and the process activation flag was set to “ALL” (therefore,the scheduling mode is transited to a secondary AG mode). If the latestAG that affected the SG was the secondary AG, the WTRU is already in thesecondary AG mode.

A primary AG mode is a scheduling mode in which only a primary AG and anRG affect the SG, (i.e., a secondary AG does not affect the SG). Asecondary AG mode is a scheduling mode in which all of the primary AG,the secondary AG and the RG may affect the SG. When in a primary AGmode, the Node-B controls the resource scheduling for only a particularWTRU using a primary E-RNTI, and when in a secondary AG mode, the Node-Bcontrols the resource scheduling for a group of WTRUs using a secondaryE-RNTI. A primary AG whose AG value is set to “INACTIVE” triggers thetransition from the primary AG mode to the secondary AG mode.

If, at step 404, it is determined that an AG is not detected, it isfurther determined whether the scheduling mode is a primary AG mode(step 406). If the scheduling mode is not a primary AG mode, (i.e., itis a secondary AG mode), the process 400 proceeds to step 446 to waitfor the next TTI. If the scheduling mode is a primary AG mode, the SG isset based on a received RG, (it is assumed that an RG is received fromthe serving RLS), and the SG generated in the previous TTI for the sameH-ARQ process (step 408). An RG received from the serving RLS isinterpreted relative to the power ratio in the previous TTI for the sameH-ARQ process as the transmission which the RG affects. If the RGindicates an UP command, then the SG is obtained by increasing theprevious power ratio by the predetermined step size. If the RG indicatesa DOWN command, the SG is obtained by decreasing the previous powerratio by the predetermined step size. If the RG indicates a HOLDcommand, the SG remains unchanged.

If, at step 404, it is determined that an AG is detected, it is furtherdetermined whether the AG is a primary AG or a secondary AG (step 410).If the AG is a primary AG, the scheduling mode is set to the primary AGmode (step 412). It is then further determined whether the AG value ofthe detected AG is set to “INACIVE” (step 414). If the AG value is notset to “INACTIVE”, (i.e., the AG value is set to a non-zero value), theSG is updated to the received AG value (step 416). It is then determinedwhether the TTI is 2 ms or 10 ms (step 418). If the TTI is 10 ms, allthe H-ARQ processes are activated (step 424) and the process 400proceeds to step 446 to wait for the next TTI.

If the TTI is 2 ms, it is further determined whether the activation flagis set to “SINGLE” or “ALL” (step 420). If the activation flag is set to“SINGLE”, the particular H-ARQ process is activated, (i.e., if theparticular H-ARQ process is inactive, the H-ARQ process becomes active,and if the H-ARQ process is active, the H-ARQ process remains active),(step 422). If the activation flag is set to “ALL”, all H-ARQ processesare activated, (i.e., inactive H-ARQ processes becomes active and activeH-ARQ processes remain active), (step 424). An active process is anH-ARQ process for which scheduled data may be sent and an inactiveprocess is an H-ARQ process for which non-scheduled data may be sent.

If, at step 414, it is determined that the AG value of the received AGis set to “INACTIVE”, it is further determined whether it is 2 ms or 10ms TTI (step 425). If it is 2 ms TTI, it is further determined whetherthe activation flag is set to “SINGLE” or “ALL” (step 426). If theactivation flag is set to “SINGLE”, only the particular H-ARQ processbecomes inactive (step 428). If the activation flag is set to “ALL”, itis further determined whether a secondary E-RNTI is configured (step430). If it is determined at step 425 that it is 10 ms TTI, the process400 proceeds to step 430. If the secondary E-RNTI is not configured, allH-ARQ processes are deactivated (step 432). If the secondary E-RNTI isconfigured, the current SG may be updated to the latest received AGvalue (step 434), (which will be explained in detail with reference toFIGS. 5A-5C). Alternatively, the SG value may not be changed and theprevious SG value may remain the same. In such case, the step 434 isbypassed and the process 400 proceeds to step 436. All H-ARQ processesare then activated and the scheduling mode is set to the secondary AGmode (steps 436, 438).

If, at step 410, it is determined that the AG is not a primary AG,(i.e., the AG is a secondary AG), it is further determined whether thescheduling mode is a secondary AG mode (step 440). If the schedulingmode is the secondary AG mode, (therefore, the secondary AG may affectthe current SG), the current SG is set based on the AG value of thereceived AG (step 442). If the scheduling mode is not a secondary AGmode, (therefore, the secondary AG may not affect the current SG), theAG value of the received AG is saved in a memory and may be used later,(which will be explained in detail with reference to FIGS. 5A-5C) (step444).

FIGS. 5A-5C illustrate exemplary Node-B scheduling with a primary AG anda secondary AG in accordance with the present invention. A Node-Btransmits either a primary AG or a secondary AG to the WTRU. Thescheduling grant mode switches between a primary AG mode and a secondaryAG mode. The primary AG always resets the current SG. The secondary AGonly affects the current SG if the current scheduling mode is set to asecondary AG mode, (i.e., when the last primary AG triggers thetransition to the secondary AG mode), or if the latest AG that affectedthe SG was the secondary AG. Hereinafter, it is assumed that the initialstate is a primary AG mode. However, the present invention is equallyapplicable to the case when the initial configuration is in a secondaryAG mode.

Referring to FIG. 5A, a Node-B first sends a secondary AG 502. Since thecurrent scheduling mode is a primary AG mode, the AG value in thereceived secondary AG 502 is saved. The next AG is a primary AG 504 withan AG value set to “INACTIVE.” This triggers a transition from theprimary AG mode to the secondary AG mode as indicated by a down arrow522.

When the scheduling mode is switched from the primary AG mode to thesecondary AG mode, the SG may remain the same as the previous SG in thetransition period of scheduling mode switching and the SG is updatedwhen the next AG, (in this case AG 506), is received. Alternatively, theSG may be set to the latest received and saved secondary AG value, (inthis example, the AG 502), in transition period of scheduling modeswitching to avoid the delay of SG update.

The next two AGs 506,508 are secondary AGs and the SG is updated withthe AG values of the secondary AGs 506, 508, respectively. The next AGis a primary AG 510. The receipt of a primary AG while in a secondary AGmode triggers a transition back to the primary AG mode as indicated byan up arrow 524.

After two primary AGs are sent, a primary AG 512 with the AG value setto “INACTIVE” is received. This triggers switch of the scheduling modeback to the secondary AG mode as indicated by a down arrow 526 and theSG may remain the same and updated when the next secondary AG, (in thisexample, the AG 513), is received. Alternatively, the SG may be updatedwith the latest secondary AG, (in this example, the AG 508), in thescheduling mode transition period to avoid the delay of SG update.

A potential problem is that the last saved secondary AG value may beout-of-date when the system stays in a primary AG mode for too long. Forexample, when the WTRU receive a primary AG 516, the system has stayedin a primary AG mode for 6 TTIs and the last secondary AG 514 may beout-of-date.

FIG. 5B shows another exemplary Node-B scheduling with a primary AG anda secondary AG in accordance with the present invention. In thisembodiment, the Node-B sends a secondary AG right before switching tothe secondary AG mode. In FIG. 5B, the transmission sequence of AGs issame to the case in FIG. 5A, except the Node-B sends a secondary AG 520just before sending the primary AG 516. The scheduling mode has beenswitched from the secondary AG mode to the primary AG mode as indicatedby an up arrow 528 when the primary AG 518 is received. The Node-B sendsthe secondary AG 520 just before switching the scheduling mode to thesecondary AG mode, (i.e., just before sending a primary AG 516 with anAG value set to “INACTIVE”). The AG value in the secondary AG 520 issaved and used when the scheduling mode is switched to the secondary AGmode as indicated by a down arrow 530 when the primary AG 516 isreceived. With this scheme, an out-of-date secondary AG may be avoided.

Alternatively, the Node-B may use a time threshold to detect anout-of-date problem as shown in FIG. 5C. The Node-B determines justbefore switching the scheduling mode from the primary AG mode to thesecondary AG mode whether the out-of-date situation exists, (i.e.,whether there was any secondary AG transmitted in the time thresholdfrom the switching point). If there was any secondary AG transmittedduring the time threshold, the Node-B sends the primary AG 516 withoutsending the secondary AG 520. However, if there was no secondary AGtransmitted during the time period, (as shown in FIG. 5C), the Node-Bsends the secondary AG 520 before sending the primary AG 516.

The time threshold may be implemented as a static value. Alternatively,the time threshold may be semi-statically or dynamically adjusteddepending on several factors including, but not limited to, a trafficcondition change rate, an interference condition variation rate, vehiclespeed, or the like. If the traffic condition or interference conditionchange rapidly, the time threshold is adjusted to reflect theenvironment changes.

FIG. 6 is a block diagram of a Node-B 600 configured in accordance withthe present invention. The Node-B 600 includes a scheduling requestprocessor 602 and a Node-B scheduler 604. The scheduling requestprocessor 602 is configured to receive and process schedulinginformation received from a WTRU. The Node-B scheduler 604 is configuredto control resource scheduling by sending a primary AG and a secondaryAG to a WTRU. The Node-B scheduler 604 controls resource scheduling foronly a particular WTRU in a primary AG mode and control resourcescheduling for a group of WTRUs in a secondary AG mode.

In the case when the SG is set to the latest received and savedsecondary AG value in transition period of scheduling mode switching inthe WTRU, the Node-B scheduler 604 sends a secondary AG before switchinga scheduling mode from a primary AG mode to a secondary AG mode asexplained hereinabove. The Node-B scheduler 604 determines whether anout-of-date secondary AG exists before switching a scheduling mode fromthe primary AG mode to the secondary AG mode and switches the schedulingmode only if there is no out-of-date secondary AG exists. The Node-Bscheduler 604 determines the existence of the out-of-date secondary AGby implementing a time threshold, which may be static or dynamicallyadjusted based on a predetermined factor.

FIGS. 7A and 7B, taken together, are a flow diagram of a process 700 ofgenerating SGs based on scheduling grant from the serving RLS inaccordance with another embodiment of the present invention. The steps702-724 are identical to the steps 402-424 in FIG. 4A and therefore willnot be repeated herein. If, at step 714, it is determined that the AGvalue of the received AG is set to “INACTIVE”, it is further determinedwhether the activation flag is set to “SINGLE” or “ALL” (step 726). Ifthe activation flag is set to “SINGLE”, it is further determined whetherit is 2 ms TTI or 10 ms TTI (step 728). If it is 2 ms TTI, only theparticular H-ARQ process becomes inactive (step 730). If it is 10 msTTI, there is no change and the process 700 proceeds to step 752 to waitfor the next TTI.

If, at step 726, it is determined that the activation flag is set to“ALL”, it is further determined whether a secondary E-RNTI is configured(step 732). If the secondary E-RNTI is not configured, it is furtherdetermined whether it is 2 ms TTI or 10 ms TTI (step 734). If it is 2 msTTI, all H-ARQ processes are deactivated (step 736). If it is 10 ms TTI,there is no change and the process 700 proceeds to step 752 to wait forthe next TTI.

If, at step 732, it is determined that the secondary E-RNTI isconfigured, the current SG may be updated to the latest received AGvalue (step 738), (as explained with reference to FIGS. 5A-5C).Alternatively, the SG value may not be changed and the previous SG valuemay remain the same. In such case, the step 738 is bypassed and theprocess 700 proceeds to step 740. All H-ARQ processes are then activatedand the scheduling mode is set to the secondary AG mode (steps 740,742).

If, at step 710, it is determined that the AG is not a primary AG,(i.e., the AG is a secondary AG), it is further determined whether theAG value is set to ” INACTIVE” (step 744). If the AG value is not set to“INACTIVE”, it is further determined whether the scheduling mode is asecondary AG mode (step 746). If the scheduling mode is the secondary AGmode, (therefore, the secondary AG may affect the current SG), thecurrent SG is set based on the AG value of the received AG (step 748).If the scheduling mode is not a secondary AG mode, (therefore, thesecondary AG may not affect the current SG), the AG value of thereceived AG is saved in a memory and may be used later, (as explained indetail with reference to FIGS. 5A-5C) (step 750).

Although the features and elements of the present invention aredescribed in the preferred embodiments in particular combinations, eachfeature or element can be used alone without the other features andelements of the preferred embodiments or in various combinations with orwithout other features and elements of the present invention.

1. In a wireless communication system which supports enhanced uplink(EU) such that a wireless transmit/receive unit (WTRU) receives anabsolute grant (AG) from a serving radio link set (RLS) via an enhanceddedicated channel (E-DCH) absolute grant channel (E-AGCH) and a relativegrant (RG) from the serving RLS and a non-serving radio link (RL) via anE-DCH relative grant channel (E-RGCH), a method for generating a servinggrant (SG), the method comprising: detecting a scheduling grant whichincludes an AG and an RG; determining whether the scheduling grant is anAG; if the scheduling grant is an AG, determining whether the schedulinggrant is a primary AG or a secondary AG; and updating an SG with an AGvalue carried by the scheduling grant if the scheduling grant is aprimary AG.
 2. The method of claim 1 further comprising: if thescheduling grant is not an AG, determining whether a scheduling mode isa primary AG mode; and if the scheduling mode is not a primary AG mode,waiting for a next transmission time interval (TTI).
 3. The method ofclaim 2 further comprising: if the scheduling mode is a primary AG mode,updating the SG based on a received RG.
 4. The method of claim 3 whereinthe RG is interpreted relative to a power ratio in a previoustransmission time interval (TTI) for the same hybrid automatic repeatrequest (H-ARQ) process.
 5. The method of claim 4 wherein the RGindicates one of an UP command, a DOWN command and a HOLD command,whereby if the RG indicates an UP command, the SG is generated byincreasing a previous SG by a predetermined step size, if the RGindicates a DOWN command, the SG is generated by decreasing the previousSG by the predetermined step size, and if the RG indicates a HOLDcommand, the previous SG remains unchanged.
 6. The method of claim 1further comprising: if the scheduling grant is a primary AG, setting ascheduling mode to a primary AG mode.
 7. The method of claim 1 furthercomprising: determining whether an AG value of the scheduling grant isset to “inactive”, whereby the SG is set to the AG value in thescheduling grant if the AG value is not set to “inactive.”
 8. The methodof claim 7 further comprising: setting a scheduling mode to a secondaryAG mode if the AG value is set to “inactive.”
 9. The method of claim 7further comprising: determining whether a transmission time interval(TTI) is 10 ms or 2 ms; if the TTI is 10 ms, activating all H-ARQprocesses and waiting for the next TTI.
 10. The method of claim 9further comprising: if the TTI is 2 ms, determining whether anactivation flag is set to “single” or “all”; if the activation flag isset to “single”, activating a corresponding hybrid automatic repeatrequest (H-ARQ) process; and if the activation flag is set to “all”,activating all H-ARQ processes.
 11. The method of claim 7 furthercomprising: if the AG value is set to “inactive”, determining whether itis a 2 ms transmission time interval (TTI) or a 10 ms TTI; and if it isa 2 ms TTI, determining whether an activation flag is set to “single” or“all”; and if the activation flag is set to “single”, deactivating acorresponding hybrid automatic repeat request (H-ARQ) process.
 12. Themethod of claim 11 further comprising: if either the activation flag isset to “all” or if it is 10 ms TTI, determining whether a secondaryE-DCH radio network temporary identifier (E-RNTI) is configured; and ifthe secondary E-RNTI is not configured, deactivating all H-ARQprocesses.
 13. The method of claim 12 further comprising: if thesecondary E-RNTI is configured, setting the SG value based on the latestreceived AG value; activating all H-ARQ processes; and setting ascheduling mode to a secondary AG mode.
 14. The method of claim 12further comprising: if the secondary E-RNTI is configured, maintainingthe current SG value; activating all H-ARQ processes; and setting ascheduling mode to a secondary AG mode.
 15. The method of claim 6further comprising: if the scheduling grant is not a primary AG,determining whether the scheduling mode is a secondary AG mode; and ifthe scheduling mode is a secondary AG mode, setting the SG to a AG valuein the scheduling grant.
 16. The method of claim 15 further comprising:if the scheduling mode is not a secondary AG mode, saving an AG value inthe scheduling grant.
 17. The method of claim 8 wherein the serving RLSsends a secondary AG before switching the scheduling mode from a primaryAG mode to a secondary AG mode.
 18. The method of claim 17 furthercomprising: the serving RLS determining whether an out-of-date secondaryAG exists before switching the scheduling mode from the primary AG modeto the secondary AG mode; and the serving RLS switching the schedulingmode only if there is no out-of-date secondary AG exists.
 19. The methodof claim 18 wherein the serving RLS determines the existence of theout-of-date secondary AG by implementing a time threshold.
 20. Themethod of claim 19 wherein the time threshold is static.
 21. The methodof claim 19 wherein the time threshold is dynamically adjusted based ona predetermined factor.
 22. The method of claim 21 wherein thepredetermined factor includes at least one of a traffic condition changerate, an interference condition variation rate and vehicle speed. 23.The method of claim 7 further comprising: if the AG value is set to“INACTIVE”, determining whether the activation flag is set to “single”or “all”; if the activation flag is set to “single”, determining whetherit is 2 ms TTI r 10 ms TTI; and if it is 2 ms TTI, deactivating acorresponding hybrid automatic repeat request (H-ARQ) process.
 24. Themethod of claim 23 further comprising: if the activation flag is set to“all”, determining whether a secondary E-DCH radio network temporaryidentifier (E-RNTI) is configured; if the secondary E-RNTI is notconfigured, determining whether it is 2 ms TTI or 10 ms TTI; and if itis 2 ms TTI, deactivating all H-ARQ processes.
 25. The method of claim24 further comprising: if the secondary E-RNTI is configured, settingthe SG based on the latest received AG value; activating all H-ARQprocesses; and setting a scheduling mode to a secondary AG mode.
 26. Themethod of claim 24 further comprising: if the secondary E-RNTI isconfigured, maintaining the current SG; activating all H-ARQ processes;and setting a scheduling mode to a secondary AG mode.
 27. The method ofclaim 15 further comprising: determining whether the AG value is set to“INACTIVE”, and determining whether the scheduling mode is secondary AGmode only if the AG value is not set to “INACTIVE.”
 28. In a wirelesscommunication system which supports an enhanced uplink (EU) such that awireless transmit/receive unit (WTRU) receives an absolute grant (AG)from a serving radio link set (RLS) via an enhanced dedicated channel(E-DCH) absolute grant channel (E-AGCH) and a relative grant (RG) fromthe serving RLS and a non-serving radio link (RL) via an E-DCH relativegrant channel (E-RGCH), a WTRU for generating a serving grant (SG), theWTRU comprising: a decoder for decoding a received scheduling grantwhich includes an AG and an RG; and an SG processor configured to updatean SG with an AG value carried by the received scheduling grant if thereceived scheduling grant is a primary AG.
 29. The WTRU of claim 28wherein the SG processor is configured to determine whether a schedulingmode is a primary AG mode if a received scheduling grant is not an AG,and wait for a next transmission time interval (TTI) if it is determinedthat the scheduling mode is not a primary AG mode.
 30. The WTRU of claim29 wherein the SG processor is configured to update the SG based on areceived RG if the received scheduling mode is a primary AG mode. 31.The WTRU of claim 30 wherein the SG processor interprets an RG relativeto a power ratio in a previous transmission time interval (TTI) for thesame hybrid automatic repeat request (H-ARQ) process.
 32. The WTRU ofclaim 31 wherein the RG indicates one of an UP command, a DOWN commandand a HOLD command, whereby if the RG indicates an UP command, the SGprocessor generates the SG by increasing a previous SG by apredetermined step size, if the RG indicates a DOWN command, the SGprocessor generates the SG by decreasing the previous SG by thepredetermined step size, and if the RG indicates a HOLD command, the SGprocessor maintains the previous SG.
 33. The WTRU of claim 28 whereinthe SG processor is configured to set a scheduling mode to a primary AGmode if the scheduling grant is a primary AG.
 34. The WTRU of claim 28wherein the SG processor is configured to determine whether an AG valueof the scheduling grant is set to “inactive”, whereby the SG processorsets the SG to the AG value in the scheduling grant if the AG value isnot set to “inactive.”
 35. The WTRU of claim 34 wherein the SG processoris configured to set a scheduling mode to a secondary AG mode if the AGvalue is set to “inactive.”
 36. The WTRU of claim 34 wherein the SGprocessor is configured to determine whether a transmission timeinterval (TTI) is 10 ms or 2 ms, and activate all H-ARQ processes andwait for the next TTI if the TTI is 10 ms.
 37. The WTRU of claim 36wherein the SG processor is configured to determine whether it is a 2 msTTI or a 10 ms transmission time interval (TTI) if the AG value is setto “inactive”, determine whether an activation flag is set to “single”or “all” if the TTI is 2 ms, and activate a corresponding hybridautomatic repeat request (H-ARQ) process if the activation flag is setto “single.”
 38. The WTRU of claim 37 wherein the SG processor isconfigured to determine whether a secondary E-DCH radio networktemporary identifier (E-RNTI) is configured if the activation flag isset to “all” or it is 10 ms TTI, and deactivate all H-ARQ processes ifthe secondary E-RNTI is not configured.
 39. The WTRU of claim 38 whereinthe SG processor is configured to set the SG based on the latestreceived AG value if the secondary E-RNTI is configured, activate allH-ARQ processes, and set the scheduling mode to a secondary AG mode. 40.The WTRU of claim 38 wherein the SG processor is configured to maintaina current SG if the secondary E-RNTI is configured, activate all H-ARQprocesses, and set the scheduling mode to a secondary AG mode.
 41. TheWTRU of claim 28 wherein the SG processor is configured to determinewhether a scheduling mode is a secondary AG mode if the scheduling grantis not a primary AG, and set the SG to an AG value in the schedulinggrant if the scheduling mode is a secondary AG mode.
 42. The WTRU ofclaim 41 wherein the SG processor is configured to save an AG value inthe scheduling grant if the scheduling mode is not a secondary AG mode.43. The WTRU of claim 34 wherein the SG processor is configured todetermine whether the activation flag is set to “single” or “all”, ifthe AG value is set to “INACTIVE”; if the activation flag is set to“single”, determine whether it is 2 ms TTI or 10 ms TTI; and if it is 2ms TTI, deactivate a corresponding hybrid automatic repeat request(H-ARQ) process.
 44. The WTRU of claim 43 wherein the SG processor isconfigured to determine whether a secondary E-DCH radio networktemporary identifier (E-RNTI) is configured if the activation flag isset to “all”, if the secondary E-RNTI is not configured, determinewhether it is 2 ms TTI or 10 ms TTI, and if it is 2 ms TTI, deactivateall H-ARQ processes.
 45. The WTRU of claim 44 wherein the SG processoris configured to set the SG based on the latest received AG value if thesecondary E-RNTI is configured, activate all H-ARQ processes, and set ascheduling mode to a secondary AG mode.
 46. The WTRU of claim 44 whereinthe SG processor is configured to maintain the current SG if thesecondary E-RNTI is configured, activate all H-ARQ processes, and set ascheduling mode to a secondary AG mode.
 47. The WTRU of claim 41 whereinthe SG processor is configured to determine whether the AG value is setto “INACTIVE”, and determine whether the scheduling mode is secondary AGmode only if the AG value is not set to “INACTIVE.”
 48. In a wirelesscommunication system which supports an enhanced uplink (EU) such that awireless transmit receive unit (WTRU) receives an absolute grant (AG)and a relative grant (RG) from a Node-B, a Node-B for supporting aserving grant (SG) processing in a WTRU, the Node-B comprising: a raterequest processor configured to receive and process a rate request froma WTRU; and a Node-B scheduler configured to control resource schedulingby sending a primary AG and a secondary AG to a WTRU, the Node-Bscheduler configured to control resource scheduling for only aparticular WTRU in a primary AG mode and control resource scheduling fora group of WTRUs in a secondary AG mode, wherein the Node-B scheduler isconfigured to send a secondary AG before switching a scheduling modefrom a primary AG mode to a secondary AG mode.
 49. The Node-B of claim48 wherein the Node-B scheduler is configured to determine whether anout-of-date secondary AG exists before switching the scheduling modefrom the primary AG mode to the secondary AG mode and switch thescheduling mode only if there is no out-of-date secondary AG exists. 50.The Node-B of claim 49 wherein the Node-B scheduler is configured todetermine the existence of the out-of-date secondary AG by implementinga time threshold.
 51. The Node-B of claim 50 wherein the time thresholdis static.
 52. The Node-B of claim 50 wherein the time threshold isdynamically adjusted based on a predetermined factor.
 53. The Node-B ofclaim 52 wherein the predetermined factor includes at least one of atraffic condition change rate, an interference condition variation rateand vehicle speed.